The present invention relates to an image display control device and the like. More particularly, the invention relates to an image display control device (image display control LSI) which adaptively reduces the luminance of display lighting corresponding to a display image and corrects an image signal to compensate for deterioration in image quality due to a reduction in luminance, and the like.
JP-A-11-65531 discloses technology which reduces the quantity of light emitted from a backlight aimed at reducing power consumption, and adjusts image data to increase the transmissivity of a liquid crystal display screen as much as possible.
JP-A-2004-310671 discloses an image correction device which uses a look-up table (LUT) in order to correct a luminance signal of a display image.
In order to simultaneously perform a reduction in luminance of lighting (e.g., backlight) and image correction aimed at preventing deterioration in image quality, it is necessary to perform a large number of calculations based on image data. Calculations may be simplified by utilizing a look-up table (LUT) which stores calculation results. However, memory access takes time. Therefore, this method cannot be used when a high-speed capability is required. For example, a method using an LUT is not suitable when a real-time capability is required, such as when reproducing a streaming image distributed by one-segment broadcasting (digital broadcasting for portable telephone terminals) using a portable telephone terminal.
A high-speed capability (real-time capability) can be ensured by causing a plurality of pieces of dedicated hardware to perform specific calculations in parallel. However, the occupied area and the power consumption of the circuit are inevitably increased.
JP-A-11-65531 takes only luminance correction into consideration during image correction which compensates for deterioration in image quality due to a reduction in lighting luminance. However, since the image quality significantly deteriorates when the chroma (color brightness (vividness)) of the image is impaired due to a reduction in lighting luminance, image correction taking not only the luminance but also the chroma into consideration is necessary.
When the amount of reduction in lighting luminance is adaptively determined corresponding to the luminance of the display image, the lighting luminance quickly changes to follow a quick change in luminance of the display image, whereby a flicker occurs. As a result, the image quality of the display image may deteriorate. In particular, since the luminance of an image frequently changes momentarily when reproducing a streaming image, a flicker (visual flicker) may occur. Therefore, it is necessary to suppress a flicker accompanying a scene change.